Industries that package their items in can or bottle-type containers usually are searching for ways to maximize production output. With the ever-increasing demand for higher production rates, surface conveyor systems have been designed that are capable of greater accumulation of the containers so that the surface conveyor can accommodate a varying backlog of the containers. For example, the infeed of the conveyor system might be several times wider than the containers so as to be able to receive the containers in random multiple width arrangement of containers. Usually, the wider the infeed conveyor is, the greater its accumulation capability will be. Hence, several container-dependent industries are now using very wide conveyor systems.
Although wider conveyor systems have helped to increase production rates, production has still heretofore been limited because the typical production line requires that containers be fed into a subsequent work station in a single file. For example, standard equipment such as inspection lights and/or electronic bottle inspectors, product fillers, container cappers or sealers, container de-cappers, and labelers all require that the container must enter in a single file. In order to narrow the container stream width from an initial multiple width of containers to single file, combiners have been developed. The smooth transfer from a wide width to single file makes the combiner one of today's most important items in the production line.
In the past, multiple flat top chains and converging rails have been used in order to combine containers from a mass of containers into a single file or row of containers. When combining light-weight containers there is a problem that the side-to-side compaction of the containers against one another causes some of the containers to levitate and lose speed because they no longer touch the conveyor chain. This side-to-side compaction also creates a problem of bridging of the containers between the side guides of the combiner so that the movement of the containers stalls, and the following containers push the containers next ahead, which tends to cause more bridging between the side rails instead of pulling the containers in spaced relationship into single file.
Also in the past, it was generally believed in the industry that glass bottle combiners must be designed to satisfy the following conditions: (1) the combiner must be at least two meters long; (2) the downstream end of the combiner must be located at least two meters upstream from the equipment it feeds; (3) the combiner must use tapered guide rails; (4) the combiner should use two chains--a 71/2 inch width feed chain and a 31/4 inch width single conveyor discharge chain; (5) the relation of the infeed chain speed to the discharge chain speed must be 66%; and (6) the combiner must always be full of bottles to maintain the bottle position that produces smooth flow. A combiner made within these six specifications typically would yield an output of 600 to 1000 bottles; 1500 cans per minute; and no more than 600 bpm for standard 12 oz. plastic bottles. Twelve ounce plastic bottles are limited to 600 bpm because of their light bottle weight, low bottle stability, high bottle compressibility and high friction that exists between the plastic bottle and the guide rails.
If the above six combiner specifications are used with an air-jet guide rail to combine light-weight containers such as 12 oz. plastic bottles, 650 bpm has been achieved. However, heretofore no one has been able to successfully combine light-weight containers at greater than 700 bpm.
For metal type containers, such as cans, Lenhart, U.S. Pat. No. 4,669,604, teaches that if objects are first arranged in an equilateral triangle on a dead plate, the objects, such as metal cans, may be formed in a single file using a vacuum source drawn through openings in the conveyor belt to hold the outside row of containers in place on the moving belt and out of engagement with the side rails while the other containers are urged in between the containers in the outside row. However, Lenhart's invention will not work properly if the containers are in a "random, helter-skelter fashion" and also requires that the cans must be pushed off the dead plate by the oncoming moving mass of cans upstream of the dead plate.